Did you upgrade Companion to version 2.28, App Inventor 2 had a large upgrade last night and if you do not upgrade to Companion 2.28 you might have issues like this. To force an upgrade Connect > Hard Reset and follow the pop up instructions.
If you did successfully upgrade Companion, did you convert your projects for Fixed sizing to Responsive sizing? Or are you using Fixed. There are known issues involving apps that switch screens and are set to Responsive sizing
https://docs.google.com/document/d/1k40Hyq6caTajy06hFPeqt-wCkWbuw_nK1duUZll2has/pub . MIT is working on this issue.
Regarding Genymotion, I cannot test. All my apps work very well using the Fixed sizing and using the stock Google supplied emulator that downloads with the AI2 installer.
Is this an issue with Genymotion? I do not know...it might be. Do your apps work on a device?
Could you run a simple test please? Create a simple Project, call it MyAI2test. Place a button on the Designer screen.
Regards,
Steve